Usualy it's "ALT and the ENTER key" at the same time. but....
depending on your Window Manager (kwm,gwm,xwm,mwm,etc..)
most modern desktops you can configure each and every "hot-key"
I made a shortcut in KDE to minimise window (CTL-F5) work in kde, except with Q3... I tried it with and without the console showing... Can you guys minimise your q3 when its fullscreen?
i play windowed all the time, so i just drop down the console which frees my mouse cursor. then i can do with the window whatever i want, like minimizing, moving, etc.